Skateboards are typically used for recreation, or transportation. They can be pushed by foot, gravity, or electrically driven. When a skateboard is used for off road purposes it is sometimes referred to as a Mountain board, or Dirt board. They are well documented in the art. Skateboards typically feature 4 small polyurethane wheels. Off-road skateboards typically feature 4 larger air filled rubber tires. A typical skateboard does not feature any form of suspension, whether being used on or off road, although some have in the past. Skateboards consist of a board typically made of wood, commonly referred to as the deck. The deck is what a rider stands on while riding a skateboard. The deck is mounted to a set of trucks that provide the axles for mounting wheels onto. Trucks allow for two wheels to be mounted on each truck, thereby providing four wheels under the deck for the rider to roll on while standing on the deck. Trucks are also the steering mechanism, for the skateboard. They are mounted in an apposing direction to provide four wheel equal steering.
Skateboards of various designs having a pair of trucks in opposing orientation are well known in the art. Typical prior art skateboard trucks consists of a base plate, a hanger, a pivot member, a pivot cup, an axle coupled to the hanger, a kingpin and bushings that allow for the tilting and rotating of the hanger with respect to the base. The bushings establish the amount of force a user must exert in order to tilt and rotate the hanger of the truck. The pivot angle of the trucks is what determines the steering ability of the trucks. For example, it is typically understood that a high pivot angle makes the trucks more sensitive to tilting and facilitates steering by tilting and a lower pivot angle makes trucks less sensitive to tilting and thereby makes the skateboard more stable.
Prior art designs of axle support mechanisms for a skateboard provide adequate performance over smooth surfaces, but can become hazardous when rocks, uneven pavement or other obstacles are encountered, resulting in the rider being ejected from the skateboard. Variations of the typical skateboard truck have utilized springs, shocks, and bushings to provide movement of the axle, thereby allowing for some limited suspension movement to mitigate this hazard. Unfortunately since both axles tend to be mechanically coupled together, a bump or disturbance action to one side of the truck will result in direct movement of the other, resulting in an adverse steering reaction that can also be hazardous.
There have been many different variations of suspension mechanisms to absorb shock, and provide the user a safer ride over rough terrain. Although some of these prior art devices may provide limited absorption when small hazards are encountered by both wheels, none have been able to provide novel attributes of the present invention regarding independent shock absorption, and ride stability.
By way of example, U.S. Pat. No. 4,152,001 issued to Christianson, was based on an axle hanger mounted on a plate shaped member. Although it does allow for limited movement of both axles together, it lacks a steering alignment mechanism to enable the hanger to maintain the steering tilt axis. As movement commences, steering geometry and stability losses it's integrity.
A more recent example is U.S. Pat. No. 9,295,902 B2 issued to Lininger, provides the same type of axle movement of the art mentioned above, but provides a steering alignment mechanism to enable the hanger to maintain the steering tilt axis. This improves stability, but does not provide independent movement of the axles.
Lastly U.S. Pat. No. 7,219,907 issued to Chang, features an independent movement of the axles due to an elastomeric compression bushing, mounted inside a centrally mounted swivel mechanism. The swivel mechanism is low to the ground, and becomes even lower when compressed; creating a ground clearance problem that is undesirable.
These know devices are not very practical for riding on steep, rough, or adverse terrain. The subject invention and embodiments has improved upon many of the limitation exhibited in prior art. The result is a device that enables the user to easily traverse terrain that would be previously difficult.